Hello, Thanks for posting, If I am not wrong, then the medical terminology for this is could be muscle atrophy. Muscle atrophy is the wasting or loss of muscle tissue. There are two types: - Disuse atrophy occurs from a lack of physical activity. In most people, muscle atrophy is caused by not using the muscles enough. People with seated jobs, medical conditions that limit their movement, or decreased activity levels can lose muscle tone and develop atrophy. Obviously not your daughter s case as she is athletic. - Neurogenic atrophy is the most severe type. It occurs when there is an injury to, or disease of, a nerve that connects to the muscle. This type of muscle atrophy tends to occur more suddenly than disuse atrophy. Examples of diseases affecting the nerves that control muscles: - Amyotrophic lateral sclerosis (ALS or Lou Gehrig s disease) - Guillain-Barre syndrome - Neuropathy - Polio (poliomyelitis) Constricted muscles can cause a great deal of pain, especially if they occur in an area of the body that you use often. Proper nutrition can help remedy this situation. Given that I am unable to examine first hand your daughter s condition, it will be hard to actually tell if your daughter is indeed suffering from muscle atrophy (as the fact that she is athletic makes it seem more like she might be suffering from an injury due to her sporting activity). She will require full medical exams as soon as possible. Hope this helps